This beautiful chapel of ease, dedicated to St James, is in Stoke Orchard, a few miles outside Cheltenham. Inside, the walls still bear traces of their mediaeval paintings. Though the colours are faded now, in their heyday they would have been vibrant, even garish. Their purpose was to illustrate the Bible’s teachings to people who couldn’t read or understand Latin, as all services in the church would have been conducted in Latin. The fact they’ve survived the rigours of the reformation of the church and the hammer blows (literally) of Oliver Cromwell’s vision of England, is astonishing. In other churches, the paintings survived only to fall foul of Victorian whitewash. Any that survive, as they do here, are incredibly fragile and increasingly rare, a fact that makes them doubly precious.

But what makes this church so special to me is that it contains a number of pilgrim crosses. The church was on the pilgrim route to Santiago de Compostela: pilgrims heading there from the north of England or from Wales would break their journey at certain points along the way, offering up prayers for a safe journey and return. This chapel is one of those stopping off points. On their way to Spain, pilgrims carved crosses in the stonework of the church, just inside the door. On their way home, they carved a circle around the cross they’d made, indicating they'd safely made it back. To me, these marks are so poignant: a tangible mark of both the faith and fragility of previous times.

My interest in pilgrims and pilgrimages started long ago, as a child taken to visit church after church, abbey after abbey. Was I the only ten year old who could spot a Saxon tower? Later, when I lived amongst Aboriginal people, I came to see correlations between pilgrim routes and the songlines. Walkabout is, arguably, a form of pilgrimage.

And now my latest book, Holy Blood, concerns itself with the holy relics housed in abbeys in the middle ages. Some relics were regarded as so sacred they attracted thousands of pilgrims, whose offerings at the shrine provided a valuable source of income for the abbey. In Holy Blood, the abbey is Hailes, near Winchcombe, a few miles from Cheltenham. It housed one of the most sacred Christian relics of all: a phial of the blood of Christ, collected at the time of his crucifixion. Pilgrims flocked to see the relic: the mere sight of it was believed to ensure salvation.

But Henry VIII, forgetting that he himself had walked barefoot in pilgrimage to the shrine at Walsingham, ordered the destruction of the relics. The Blood of Hailes was removed and tested, and declared to be a fake. A short time later, the Abbey itself was Dissolved, the land given away, and the buildings dismantled.

The plot of Holy Blood came about when on a visit to Hailes, one gloriously sunny summer day, I found myself wondering, ‘What if the Holy Blood of Hailes wasn’t destroyed during the Dissolution of the Monasteries, after all? What if it survived somehow?’

And from there I started reading, widely, about pilgrims and pilgrimages, the Dissolution, monastic life, and what happened to people who continued to believe in relics and the Catholic church. And I did my own pilgrimage, to Walsingham, in Norfolk. Not barefoot like Henry VIII, but still. It was as I imagined pilgrim sites to be in the past: groups travelling together with their priest, some solemn and overawed, others laughing and with a ready quip; the sales of badges and stickers to proclaim ‘I was there’; a strangely festival atmosphere and a disconcerting rubbing shoulders of the sacred and the profane.

But as I stood in the Slipper Chapel, silent and overawed by the press of history, I understood how it might have felt to a mediaeval pilgrim, weary and travel stained, to reach his destination at last. And I saw how embodied an experience pilgrimage is, to undergo the rigours and perils of the journey, which could easily last for months. No wonder they bought badges to mark the event. I’d done nothing more strenuous than sit in a car, but I too, bought a badge, to mark my pilgrimage.